The invention relates to a high altitude G-valve which is used to control inflation of a pilot's G-pants in response to both altitude and G-force.
It is known that pressurizing a lower anti-G garment (G pants) in conjunction with breathing at elevated gauge pressure increases the amount of time a pilot can withstand low surrounding ambient pressure. The pressure in the G-pants improves the return of blood from the legs to the heart by reducing the pooling of blood in the lower extremities caused by pressure breathing.
It is also known that the inflation pressure in the G-pants should be varied both as a function of G-load and altitude in order to provide maximum protection for the pilot.
Combination breathing regulators and anti-G garmet valves (BRAG valves) which perform this function are known in the art. BRAG valves operate by delivering a signal from a G-valve which is a function of a pressure signal received from a breathing regulator. Since the breathing regulator pressure signal is dependent on altitude, the BRAG valve produces a signal which is a function of both G-load and altitude. This arrangement requires communication between the breathing regulator and the anti-G valve. In some cases, it has been proposed to mount the two units adjacent to one another so that the need for auxiliary coupling hardware and the attendant added complexity and cost could be avoided. Modern fighter aircraft cockpits are already crowded however, and it is often impossible to find the necessary panel space in which to mount such a combination unit. Alternate solutions separate the two units to locations where smaller panel spaces are available, but electrical or pneumatic communication lines are still required and the complexity, cost and weight of the coupling hardware are strong deterrents to this approach.
It would accordingly be desirable to provide a G-valve used to control the pressure in a pilot's G-pants which varies its output as a function of altitude without the space and cost disadvantages associated with the use of a separate breathing regulator in conjunction with the G-valve.